Abstract

Background

Following from previous work suggesting that neurobehavioral features distinguish
fragile X and idiopathic variants of autism, we investigated the relationships between
four forms of repetitive behavior (stereotypy, self-injury, compulsivity, ritual behavior)
and caudate nuclei volume in two groups: boys with fragile X syndrome, a subset of
whom met criteria for autism, and a comparison group of boys with idiopathic autism.

Results

For boys with idiopathic autism, left caudate volume was modestly associated with
self-injury, while both compulsive and ritual behaviors showed significant positive
correlations with bilateral caudate nuclei volumes, replicating previous results.
For boys with fragile X syndrome, there was no such association between caudate volume
and compulsive behaviors. However, we did identify significant positive correlations
between self-injury total scores and number of self-injury topographies with bilateral
caudate nuclei volumes.

Conclusions

These findings suggest a specific role for the caudate nucleus in the early pathogenesis
of self-injurious behavior associated with both idiopathic autism and fragile X syndrome.
Results further indicate that the caudate may be differentially associated with compulsive
behavior, highlighting the utility of isolating discrete brain-behavior associations
within and between subtypes of autism spectrum disorder.